This invention relates to improvements in the treatment of animal litter with alum to reduce the generation of ammonia in the litter. More particularly, this invention relates to the addition of a deliquescent salt to alum to increase the absorption of water by the alum to speed the reaction of alum with ammonia.
Moore, Jr., in a series of U.S. patents, has explained that animal litter or manure, particularly from farm animals such as poultry and pigs, contains ammonia and phosphates. The amounts of ammonia given off into the atmosphere adversely affects farm workers, and even the animals themselves. When large amounts of ammonia are present in the atmosphere of animal enclosures, the result is lower weight gain and higher mortality rates for the animals.
Thus alum (aluminum sulfate), having the formula Al2(SO4)3. nH2O wherein n above 1 and typically is about 14-18, has been used to reduce the pH, and thus the ammonia generation, of manure and animal bedding material. Alum, either in solid or liquid form, will lower the pH of the manure by hydrolysis and will convert ammonia to ammonium ions. Ammonium ions will react with sulfates to form ammonium sulfate; the latter is a water soluble nitrogen fertilizer and can be used as such. Desirably, the amount of ammonia present in the atmosphere of an animal enclosure should be held below about 25 ppm. The use of alum for this purpose has an added advantage in that the soluble phosphates present precipitate in the presence of aluminum and thus the soluble phosphate content of manure is also reduced by this treatment. Soluble phosphates are known to seep into ground water or are carried in surface runoff water. In either case, this presents a substantial environmental problem.
Dry alum can require up to two weeks to absorb sufficient water from the air or surrounding litter to initiate the reduction of the pH of litter and thereby reduce ammonia production. Alum can be mixed with water and sprayed onto manure in an effort to accelerate its function, but this may require additional handling and it reduces the flexibility of the application timing with respect to the placement of chicks, for example, in an enclosure. The addition of water also introduces a detrimental effect on the humidity of the house and the litter.
Other sulfates can be used in place of alum or in conjunction therewith, but they must have or must cause, a low pH. Thus iron sulfate can be used, but is undesirable from a bird health standpoint if the iron sulfate is ingested in excess.
In accordance with the present invention, we have discovered that a deliquescent salt, when added to dry alum, can improve the absorption of water by the alum, thereby solubilizing the alum, and allowing the alum to react with ammonia. The time required for the solubilization of alum is called the activation time, and it indicates absorption of water by the alum. This activation time can be reduced from about two weeks in a dry atmosphere to as little as twenty-four hours when a deliquescent salt is added to the alum. The presence of the deliquescent salt also improves the uniformity of the moisture in the litter composition.